CD1284 Datasheet, PDF (133/176 Pages) Intel Corporation – IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports

IEEE 1284-Compatible Parallel Interface Controller — CD1284
7.5.8
Receive Timeout Period Register
Register Name: RTPR
Register Description: Receive Timeout Period
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Binary Count Value
Bit 2
8-Bit Hex Address: 21
Default Value: 00
Bit 1
Bit 0
The RTPR determines the time period used for the NNDT (no new data timeout) and the ‘no new
data’ timeout. The timeout counter is loaded from this register whenever a new character is placed
in – or the last character is removed from – the receive FIFO. The counter decrements on each tick
of the prescaler counter (PPR). A service request is generated if the count reaches zero and:
• Either an NNDT if the FIFO is empty and the NNDT is enabled, or
• A Good Data service request is generated if there is data in the FIFO
In either case the timeout period has expired before the FIFO reaches the programmed threshold.
7.6
7.6.1
Special Character Registers
The four special character registers, SCHR1–SCHR4, contain the character patterns used for
various character matching and flow-control functions. Each 8-bit character is right justified, that
is, comparison occurs from right to left, and all bits are compared. Any unused bits must be ‘0’.
SCHR1 and SCHR2 serve the additional function of defining the XON and XOFF characters,
respectively, used for in-band flow control.
Special Character Register 1
Register Name: SCHR1
Register Description: Special Character Register 1
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Special Character 1
Bit 2
8-Bit Hex Address: 1A
Default Value: 00
Bit 1
Bit 0
SCHR1 defines the XON character.
7.6.2
Special Character Register 2
Register Name: SCHR2
Register Description: Special Character Register 2
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Special Character 2
Bit 2
8-Bit Hex Address: 1B
Default Value: 00
Bit 1
Bit 0
SCHR2 defines the XOFF character.
Datasheet
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